There are many applications for digital cameras which are interfaced to computers. A digital camera typically operates by acquiring a series of images from a suitable imaging array. In some applications it is desirable to operate two or more digital cameras in a synchronized manner so that the video cameras acquire images substantially simultaneously. For example, when using two cameras to acquire stereo images of moving objects, the positions of the objects can be more accurately ascertained if both cameras acquire images at the same time.
The resolution of video cameras is improving. With other factors equal, higher resolution cameras produce more data than do lower resolution video cameras. The sheer volume of data produced by multiple high resolution video cameras is beyond the capacity of many current high-speed data buses of types which it is convenient to use in interconnecting video cameras and data processing devices. This forces designers of systems which require multiple video cameras to either distribute the video cameras across multiple buses or live with one or more of: lower resolution images, lower frame rates, or expensive proprietary interfaces.
One could interconnect the cameras directly on a separate wiring system which carries a synchronization signal but this is inconvenient, and it also makes it difficult to achieve proper overlap of acquisition and transmission of frames because the time at which integration will occur is not known. Further, especially in factories or other electrically noisy environments such systems can be susceptible to picking up electrical noise.
Where digital cameras are distributed across multiple buses there is the difficulty that for certain applications it is necessary to maintain the cameras operating synchronously with one another. In various applications other types of time-sensitive devices such as sound recorders, video displays, and other data acquisition or output devices need to be operated in synchrony with one another.
There is a need for ways to synchronize cameras and other time-sensitive devices which are on different buses.